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BQ28Z620: Iq consumption in sleep mode

Vasyl Vorobei
Intellectual 470 points
Part Number: BQ28Z620
Other Parts Discussed in Thread: BQSTUDIO, EV2400

Tool/software:

Hi. I have a few questions related to the sleep mode.

Firstly, the consumption. The datasheet mentions that Iq = 80 uA is achievable:

However, I'm having trouble validating that value.

Gate leakage in my case is 100 nA per MOSFET (so, 200 nA in total). No communication, no pull-up resistors on the I2C bus.

Initially, I observed the average sleep consumption at a 400 uA level. After studying the TRM, I was able to identify that the PMPDRV bit is turned off by default (and by the way, it is marked as RSVD in the bqstudio):

With PMPDRV=1 and the EV2400 disconnected, the consumption drops to ~18 uA, which is notably better than the datasheet indicates. A flat base of ~9 uA and 65 mA short pulses (possibly due to the MOSFET gates recharging).

So, in summary, it is unclear why the result is so much better than the declared typical case. This value is significant for my project because we can't utilize the shutdown mode timer due to business requirements, and currently, I lack a firm understanding of what is happening.

My second question relates to the bqstudio. The TRM mentions that the "Voltage time" and "Current time" parameters could be in the range of up to 255 seconds. But the bqstudio only allows you to set these values:

The golden image for this setup (for now, it's not fully configured, just the bare minimum):

0243.2620_1_00-bq28z620R1.zip

Best regards, Vasyl

  • 0
    TI__Mastermind 24851 points

    Hello, 

    Please send me an annotation of your schematic as to where and how you are measuring the gauge iq. 

    Additionally, the gauge iq reported is the average iq over at least a 30 second interval. 

    Regards, 

    Jonny. 

  • 0 in reply to Jonny
    Intellectual 470 points

    Hi Jonny.

    I will share the schematic in DM, waiting for your request approval.

    Regarding the 30-second interval for measurement, as shown in my screenshots, the logging time exceeds 40 seconds, so it must be enough to evaluate correctly.

    Regards, Vasyl.

  • 0 in reply to Vasyl Vorobei
    Intellectual 470 points

    I might add a small but interesting update.

    The original measurement was conducted with firmware version 1.0.0. After updating this exact board to 1.0.1, there is a significant current increase; however, it's still smaller than the datasheet:

    The short pulses remain ~65 mA, but the flat base has increased from ~9 μA to ~37 μA.